Dwayne Johnson and Jimmy Fallon reunite a military family

Dwayne 'The Rock' Johnson reunited a military family for Christmas on The Tonight Show with Jimmy Fallon, causing tears of joy from everyone.

The Moana star is involved in several charities that help those serving in the armed forces, and in the latest episode of the US talk show surprised one veteran in particular.

Karina Kabalan is a producer on the show as well as an Army vet whose Air Force husband is currently deployed overseas.

At the end of Johnson's segment with Fallon, he asked permission to help out a member of the audience.

"I would love to give back to a military family that's actually here," Johnson told the audience, before he and Fallon pretended to search the crowd, until they went into the production room, where they surprised Karina with a visit from her husband Todd.

"You guys have been living apart for the past year-and-a-half because [your husband's] 5000 miles away," Johnson told Kabalan.

"[Jimmy and I] wanted to thank you and your husband for your service and your sacrifice, and I personally heard you are the most amazing person. And we wanted to bring your husband home for the holidays."

As the two embraced and wept, Fallon exclaimed he was "losing it right now" as he rubbed away his own tears.